Safety device for hydraulic mechanisms



Get. 4, 1932. F. c. wnLsoN SAFETY DEVICE FOR HYDRAULIC MECHANISMS Filed NOV. 22. 1929 aww/m11,

Patented ct. 4, 1932 l i Y n i FRlANK C.A WILSON, OF ARCADE,V NEW YORK FFICE SAFETY DEVICE FOR HYDRAULIC MECHANISMS Application led' November 22, 1929. Serial No. 409,175.

This invention relates to improvements in Figure 2 is a` vertical section taken alon,c hydraulic mechanisms and in particular to a line 2 2 of Figure 1. safety device for such a mechanism which is l Figure 3 is an enlarged sectional view taken adapted to release the pressure behind lthe along line of Figure 2.

5 working piston of the same at a point in its Figure l is avertical section taken through Working stroke when a continued movement the fluid reservoir and the hand pump in com-v of the piston would likely result in the blowmunication therewith. Y ing out of the head of the cylinder. rlhe invention is illustrated in connection lt has been proposed heretofore, in order with an arbor press A. It is tobe understood, 10v to avoid blowing out the cylinderl head of however, that it may be utilized inany type mechanisms of this kind to provide ports in of mechanism which is provided with aworkthe side walls of the cylinders at points where ing cylinder and av piston actuated member theyewould be in open communication with which forms the movable member of vthe chambers behind the piston when'the piston mechanism.

had reached a point in its working stroke ln the embodiment illustrated, the arbor beyond which it would be dangerous to conpress A includes in general a working cylin tinue, the ports being normally on the oppoder C a movable member D and a work supsite side of the piston from the working port S, all the parts named being mounted chamber ofthe cylinder` and being placed upon a suitable frame including upright legs Vin direct communication with the working 5 which may be of channel form. 7

chamber when the piston passed them in its The cylinder C is preferably suitablyv working stroke. This type of construction7 mounted between cross members 6. The work however, has the objection that the seali-ng SupportS fixed uponsimilar cross mempacking which is usually in the form of a bers 6af which are adjustable to position the 2'5' leather Washer is Often mutilated by portions support S at the desired distance from the 5 of the same being out off by or blown out movable member D of thedevice. through such ports, the result being that the .The Worklng cylinder C is suitably consealed relation between the walls of the cylinneoted as by a feed pipe 7 to a-iluid reservoir f der and the piston is vbroken and the fluid 8- In thls form of apparatus it is the pracactuating medium is permitted to escape past tice to utilize compressed air for light pressthe piston withontaecomplishing any work. ing operations and when this method of op`` llfhe object of the present invention Vis to eration is resorted to, compressed air is adavoid the mutilationzof the sealing'parts of mittedintothe fluid reservoir 8 through a t the piston and proposes a construction in Supply plpe 9 the fluid medium 10 in the which the pressure behind the working piston reservoir being then forced out through the is permitted t0 escape, when the piston has discharge Yopening 11 Vin the reservoir and reached the limit to which it can mo-vewith through the opening 12 in the hand pump safety, byaport whichY extends through the cylinder into the feed pipe 7 by which itis body of the piston, the escaping medium/be conducted to the working cylinder C. How- 40 ing conducted by a suitable return pipeback ever, some pressing operations require great- 90 to the fluid reservoir. I er pressure than can be practically obtained Further objects are to provide a safety deby compressed air and in these cases it is vice of the type described ofsimple construepreferred to employ a hand pump vH having gtion, inexpensive to manufacture and which a plunger 12a and an operating handle 13, can be readily applied to the desired mechathe handle 13 being preferably pivoted to 95 nism. the head of the fluidreservoir as by the link The invention is illustrated in the accomL 14. In any event, whether the fluid medium panying drawing in which: Y 10 be forced through the feedpipe 7l by com Figure 1 is a perspective of an arbor press pressed air or by the hand pump H, the pisshowing one application of the invention. ton P will be forced to the lower end of its 100 Y v working stroke which is a short distance above the position shown in Figure 2. Upon the completion of the working stroke, the member D may be returned to its normal position by opening the valve 20a, in the drain pipe 20?). This will permit the spring 15 which is positioned in an annular recess 16 in the lower head of the cylinder to force the piston tothe upper position of its stroke, the fluid medium behind the same being returned to the reservoir 8 through the feed pipe 7 and the drain pipe 29?), it being un'derl stood, of course, that by the operation o f the piston P the movable member D of the de` vice will be a'ected in a like manner.

In devices of this character it is the practice to provide the piston with a flexible sealing gasket of leather or the like which is adapted to form a tight seal between the piston and the cylinder, the sealing member being, in the present instance, illustrated at 18 in Figure 2.

In order to avoid blowing out the lower cylinder head 17 by too great a downward movement of the piston P, I propose to release the pressure behind theV piston at a time during its working stroke when a further movement would likely result in the blowing out of the Vlower cylinder head. Heretofore it has been proposed, in order to avoid this danger, to provide ports in the wall which, upon the piston passing them would release the pressure in the cylinder. This method of avoiding the danger is objectionablev as the flexiblel sealing member would be cut by passing over the ports or mit the escape ofthe fluid mediumfrom be hind the piston, the escaping uid being returned to the fluid reservoir by thereturn` pipe 20`to enable its subsequent reuse. p

'Ihe duct 19, mentioned heretofore,'is normally closed by a ball valve 21 and is preferably formed longitudinally in the reduced end of the working member D about which the piston P is fitted andretained thereon as It is in open communication at its by nut 2a. lower end with a transverse bore 22, the said duct and bore providing a T-shaped recessY within which is positioned the ball valve actuating means. Y The said means includes a is carried by a cross transverse bore 22.

In the normal operation of the press, the working member D functions in the usual manner and the safety device is inoperative. If for any reason, however, the piston P is permitted to move downward to a greater extent than is safe, the cross pin 24: will strike the shoulder 25 formed in the lower piston head 17 and move relatively upward in the bore 22,l this movement, of course, being imparted to the stem 23 and the ball 21 to raise the ball from its seat. Thereupon, the fluid medium behind the piston P will flow around the ball 21 through the duct 19 and the transverse bore 22 and into the annular recess 16 from whence it is returned to the reservoir 8 as described.'y The ball valve 21 may be con? fined in bore 19 in thereduced end of the workingmember D in any suitable manner as by the apertured plug 26 which is preferl[ably threaded in the upper end of saidmem-l Having described my invention, I claim: A hydraulic mechanism including a cylinder having a piston adapted to operate the movable member of the mechanism and being 1n communication 'with a fluid reservoir, means for supplying fluid from said reservoir to said cylinder under pressure to operate said piston vand the movable member connected thereto, said member having a duct'- in communication with said reservoir and openpin 24 positioned in the ing into said cylinder on the opposite side of said piston, said duct being normally closed by a ball valve, a stem movable longitudinally in said duct for operating said valve, a cross pin positioned in a bore in said movable member and (3o-operating with said stem, the lower head of said cylinder having aninwardly projecting annular shoulder which provides an lannular drain chamber, said cross pin being adapted to engage said shoulder when said movable member approaches the safe limit of its range of movement to open said valve and permit the operating iuid to escape-'through said -duct to said drain chamber, a pipe'for returning the fluid from said chamber to said fluid reservoir andv a spring in said chamber arranged about saidl annular shoulder which is com-'-` pressed during the working stroke ofsaid piston and which is adapt-ed to return the latter toits' normal position after said working' stroke. 1

In testimony whereof I alix my signature.

FRANK C. WILSON.

stem 23 upon which the ball 21 is adapted to rest when the duct 19 is opened to release the pressure behind theY piston P.Y Thestem 23` y i Y 1er 

